The invention relates to an apparatus for the controlled feeding and taking-off of a thread into or out of a thread treatment section. There is described herein apparatus, for the controlled feeding and taking-off of a thread into or out of a thread treatment section, with delivery means provided in front and behind the thread treatment section, which delivery means comprise tapered rolls the peripheries of which bear upon one another along surface lines, and a thread guide member which can be moved to and fro along a thread drawing-in gap formed between the tapered rolls.
The apparatus of this invention serves to let the thread pass through a thread treatment section, such as, for example, the heating zone of an arrangement for a thermal treatment of a thread or the heat-setting of a thread, in a controlled or differential tension state, more especially when length or tension variations are produced either by the thread treatment as such, or when particular length or tension variations are required to be achieved during such thread treatment. Thus, for example, British Patent Specification No. 689 175 contains a description of a heat setting arrangement in the form of an elongated heating zone through which the thread is passed, to which independently controllable thread delivery means are assigned both at the inlet and outlet in order to be able to pass the thread in a given tension state through the heating zone as a function of set delivery speeds of the delivery means. Separate drive units or drive transmission members and separately operating regulating or control arrangements are required for the two delivery means in the case of this known apparatus in which the delivery means comprise substantially cylindrical delivery rolls or rollers.
There is described in British Patent Specification No. 1164852 a delivery means provided ahead of a thread treatment section, which means comprises a tapered drive roll driven from outside and a tapered counter-pressure roll pressed by spring force to bear upon this tapered drive roll. A thread guide member is assigned to these tapered delivery rolls, which member can be moved to and fro along a drawing-in gap between the two tapered rolls. When this thread guide member is moved in a direction towards the largest diameter of the two tapered rolls this thread guide member takes along the thread passing through the drawing-in gap, as a result of which action the thread is shifted into the range of higher peripheral speeds so that the thread running speed is also raised. On movement of the thread guide member in a direction towards the smallest diameter of the tapered rolls it is similarly possible to reduce the thread running speed. The control of the thread guiding member is effected by a regulating or control member which responds to the tension of the thread passing through the thread treatment section.
German Pat. No. 24 59 239 deals with a delivery means of similar design and a similar mode of operation, in conjunction with a heat setting arrangement in the form of a heating tube through which a thread requiring treatment is required to pass through in a substantially tension-free state.
An object of the invention is to provide a simply-designed apparatus for the controlled feeding and taking-off of a thread into and out of a thread treatment section through which the thread is required to pass in a controlled tensioned state, whereby only one common drive roll is necessary for the delivery means both ahead and behind the thread treatment section, whilst there is provided the facility for setting and maintaining a preset differential tension state within the thread treatment section, such as for example a heat-setting section.
According to the invention, there is provided apparatus for the controlled feeding and taking-off of a thread into or out of a thread treatment section, with delivery means ahead of and behind the thread treatment section, which delivery means comprise tapered rolls, bearing upon one another along surface lines, and a thread guide member which is movable to and fro along a thread drawing-in gap formed between the tapered rolls, characterized in that for forming feeding-in delivery means and take-off delivery means two tapered counter-pressure rolls are assigned to a tapered drive roll which can be driven from outside, and in that two thread guide members are disposed in front of or behind the respective drawing-in gaps between the tapered drive roll and the tapered counter-pressure rolls.
For the case in which the running-in and running-out thread portions in the drawing-in gaps between the tapered rolls are exactly opposite to one another it is safeguarded that within the thread treatment section, such as for example a heating section, the thread feeding-in speed equals the thread-take-off or thread drawing-off speed, so that such a thread is exposed to the relevant treatment in the thread treatment section without additional tensioning during the relevant treatment.
When it is, however, required for a thread to be, for example, additionally tensioned within the treatment section, the two thread guide members may be reset in such a way that the thread entering the treatment section is moved towards the smallest diameter of the tapered rolls and the thread leaving the treatment sections is moved towards the largest diameter of the tapered rolls, as a result of which the inlet speed of the thread becomes slower than its drawing-off speed. This results in the thread experiencing a stretching action in the treatment section, such as for example a heating zone. Through a swivelling of the two thread guide members in an opposite direction it is similarly possible to raise the inlet speed of the thread relatively to its drawing-off speed.
The axes of the tapered drive roll and of the two tapered counter-pressure rolls are preferably in a common plane, with the thread guide members disposed one at each side of this axis plane.
Preferably, in order to require only a single control or regulating arrangement, the two thread guide members may be fixed on a common rotatably-mounted supporting or holding means.
In order to safeguard a central running in of the thread into the respective drawing-in gap for every swivel setting of swivellable thread guide members, said thread guide members are preferably in the form of thread guide forks.
The aforesaid rotatably-mounted supporting or holding means is preferably arranged and the thread guide members are preferably formed such that, on resetting of the one thread guide member in a direction towards the largest diameter of the tapered drive roll the other thread guide member is moved in a direction towards the smallest diameter of the tapered drive roll.
To apparatus constructed in accordance with the invention, there is preferably assigned a deflector roller which is used for forming a thread loop between the two drawing-in gaps whereby these thread loops as a whole, or only one of its two loop limbs, are lead through the thread treatment zone, consisting for example of a heating zone.
The thread fed into, and pulled out again from, a thread treatment section, such as for example a heating zone, by delivery means constructed in accordance with the invention may come from any kind of yarn feed or also from some other processing station. The thread leaving the thread treatment section is as a rule led to a winding arrangement. The necessarily occurring speed differences and/or slip conditions within the winding arrangement and also a taking up onto bobbin elements of e.g. coned shape, cause the setting up of an imbalance between fed-in and wound-off thread. This irregularity may be the cause of different thread tensions between the run-out from a delivery means constructed in accordance with the invention and the winding arrangement. In order to eliminate such thread tension variations in this zone and also to permit generally adaptation to any timewise slowly variable processing speed, the foresaid common rotatably-mounted supporting or holding means for the thread guide members may be so supported that it can be shiftable in the axial direction of the tapered drive roll. This feature provides the possibility of, for example, shifting the rotatably-mounted supporting or holding means, and thereby the two thread guide members, in directions towards the largest diameters of the tapered rolls when the thread tension increases between the run-out from the delivery means constructed in accordance with the invention and a winding arrangement as a result of which the overall thread running speed is raised and thereby the increase in thread tension ahead of the winding arrangement is counteracted without affecting differential conditions of the thread speed in the thread treatment section.
Also, according to the invention, there is provided apparatus for the controlled feeding and taking-off of a thread into or out of a thread treatment section, said apparatus comprising: (a) an externally-drivable tapered drive roll and two tapered counter-pressure rolls bearing upon the drive roll, the thread travelling to the thread treatment section engaging between the drive roll and the one counter-pressure roll, and the thread travelling away from the thread treatment section engaging between the drive roll and the second counter-pressure roll; and (b) thread guide means movable to cause, to vary thread tension, movement of thread along the tapered drive roll.